When Marconi first popularized the radio, no one expected it to go far – literally. Radio waves ought to be stopped in their tracks by the curve of the Earth. Marconi proved they weren't, but no one knew why.

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Radio technology offered people a whole new way to experience the world. They could, communally, hear single performances. One record could be played to hundreds of thousands of people. And, without laying any cables, or any connecting wires, sound could be transmitted anywhere through invisible waves.

Oh, not anywhere, people protested. No matter how powerful Marconi, or anyone else, made radio waves, they couldn't magically curve around the Earth. Radio waves would be limited by a horizon, or people would have to set up radio towers relaying a signal from one place to another. Either way, they had limited utility.

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Guglielmo Marconi disagreed. He believed radio transmissions could travel farther than anyone imagined, and he would prove it. Marconi set up a radio station in Cornwall and stationed himself in Newfoundland. To pick up the signal he used an antenna that had to be elevated with a kite. The operation was chaotic, and for a long time, unsuccessful. And then Marconi picked up a single message in morse code – dot dot dot. The Cornwall station was transmitting the signal – S in morse code – again and again, and Marconi picked it up. He didn't know how he had picked it up. Anyone who worked the physics on it knew it was impossible. The experiment showed something was happening that no one had counted on.

Years later, they figured out what. The ionosphere is an atmospheric layer of atoms whose electrons have been stripped off them by the radiation put out by the sun. These ions, and their electrons, for a kind of solid barrier for low-frequency waves, including radio waves. The radio waves in Cornwall would bounce off the ionosphere, and then off the ground, and then off the ionosphere again, traveling across the Atlantic, towards Marconi and his kite. Today, the ionosphere is one of the reasons why we get long-range radio broadcasts. It's also why the stations our radio stations pick up "change" at night. Without solar activity the ionosphere calms down, and acts as a more efficient bouncer, at night. A far-away station that gets drowned out by more powerful local signals during the day will, at night, be able to reach a geographically wider audience.